In the art of automobile suspension systems, it is known to apply a resistive force to counteract and help control body motions due to lateral forces when the vehicle deviates from a straight path. Furthermore, it is known to apply these resistive forces through a medium which links the opposite wheels of one axle. For example, in a known sway bar system, the resistive force is created by the use of a U-shaped bar having opposite ends connected to respective wheels and a central portion secured to the frame of the automobile. Roll of the automobile about its roll axis produces a twist in the sway bar which resists that roll. While a sway bar is used primarily to resist roll of the automobile, it can also be used to help the location of suspension components, as an auxiliary function. It is recognized in the field of suspension design that compromises have to be made regarding the stiffness of the U-shaped bar because a bar that is stiff enough to resist roll during hard cornering unloads the inside wheel and sacrifices suspension independence.
It is also known to provide a bar in the shape of a "Z" for controlling the motion of wheels of an automobile. In this arrangement, such as that shown in U.S. Pat. No. 3,315,952 (Vittone), a forwardly directed end of a "Z" bar is attached to one wheel, a rearward-directed end of the bar is attached to an opposed wheel, and the central section is attached to the frame of the automobile. In this arrangement, an upward force on the bar applied by one of the wheels causes a downward force on the opposite wheel. Thus, a bar of this shape tends to keep an inside wheel on the ground as an automobile body rolls when moving in a curve without providing the resistance to roll motions as in the U-shaped sway bar described above.
The actions of the traditional U-shaped sway bar and the Z-shaped bar are thus contradictory and these bars have not been used in conjunction.